Touch panels are transparent or opaque input devices for computers and other electronic systems. As the name suggests, touch panels are activated by contact from a user's finger, a stylus, or other devices. Transparent touch panels are generally layered over display devices, such as cathode ray tube (CRT) monitors and LCDs, to create display devices. These display devices are increasingly used in commercial applications such as restaurant order entry systems, industrial process control applications, interactive museum exhibits, public information kiosks, pagers, cellular phones, personal digital assistants (PDAs), video games, and the like.
The dominant touch panel technologies presently in use are resistive, capacitive, infrared, and acoustic touch panels. FIG. 7 is a cross-section of a conventional display device employing a resistive touch panel. The display device 1 includes a flat panel display (FPD) 16 and a touch panel 10 attached on a display surface 160 of the FPD 16 via an adhesive material 18.
The touch panel 10 is a resistive touch panel, which includes a first substrate 11 and a second substrate 12 opposite thereto. A first conductive coating 13 and a second conductive coating 14 are respectively applied on inner surfaces of the first and the second substrates 11, 12. An adhesive 15 is arranged at peripheral areas of the first and the second conductive coatings 13, 14 adhering them together. A plurality of spacers 17 are applied between the first and second conductive coatings 13, 14, separating the first and second conductive coatings 13, 14, and avoiding electrical contract therebetween unless the touch panel 10 is contacted.
FIG. 8 is a top plan view of the first and second conductive coatings 13, 14. The first conductive coating 13 includes a plurality of first resistance lines 131 arranged along an X-axis of a rectangular Cartesian coordinate system, first and second electrode bars E1, E2 disposed at the left and right ends of the first resistance lines 131, and a pair of wires X1, X2 connected to the first and second electrode bars E1, E2, respectively. The second conductive coating 14 has a structure similar to the first conductive coating 13. However, a plurality of resistance lines 141 are arranged along a Y-axis, third and fourth electrode bars E3, E4 are disposed at the upper and lower ends of the second resistance lines 141, and a pair of wires Y1, Y2 are connected to the third and fourth electrode bars E3, E4, respectively.
In operation, a voltage difference is applied to the pair of wires X1, X2, and voltage gradients are generated on the first resistance lines 131. Using the wire Y1 as a grounding wire, a voltage of a point corresponding to the first resistance lines 131 where a contact occurs can be detected by the wire Y1. Then an X-coordinate of the contact point can be determined by an analyzing circuit (not shown) according to the detected voltage level. In a similar manner, application of a voltage deference to the pair of wires Y1, Y2, and detecting a voltage of the contact point via the wire X1, a Y-coordinate of the contact point can be confirmed.
In the 4-wire resistive touch panel 10, the four wires X1, X2, Y1, Y2 apply voltage signals to the first and second conductive coatings 13, 14, respectively, detecting voltage signals of the contact point. However, such 4-wire resistive touch panel has a relatively complex driving method, and requires that the analyzing circuit has the same number of driving wires corresponding to the four wires X1, X2, Y1, Y2. Thus, the touch panel and corresponding analyzing circuit have complex circuit structures.
Accordingly, what is needed is a touch panel which can overcome the limitations described.